1. Field of the Invention
The present invention generally relates to the technical field of radio communications, and particularly relates to distribution systems, distribution apparatuses, terminal apparatuses and methods which distribute a common control signal. The common control signal is a control signal which includes system information required for accessing a communications system in a region which can be used by one or more radio communications systems.
2. Description of the Related Art
In this type of technical field, studies of communications schemes using a cognitive pilot channel (CPC) are being pushed forward. For these schemes, a cognitive pilot channel is transmitted to each of multiple regions in which one or more communications systems are being operated. The cognitive pilot channel includes information on radio systems used within each region, radio schemes, frequencies, etc., thereof. The cognitive pilot channel is used, so that basic parameter information of a radio system which can be connected to by a terminal apparatus is relatively easy to obtain for the terminal apparatus. Moreover, the cognitive pilot channel may be used to flexibly deal with a change of some of parameters allocated to a radio system on a fixed basis (frequency, etc.) that was difficult in the past (because it suffices to change control information). The cognitive pilot channel also provides an advantage that it may be applied without changing the terminal apparatus itself. Therefore, a technique using a cognitive pilot channel can be adopted to flexibly respond to decreased price of a terminal apparatus, and a radio system parameter change. The radio system parameter change may be dealt with flexibly, so that improved utilization efficiency may also be expected.
In the present technique, an area covered by a distribution station (which may be shared for use with a base station apparatus) is divided into multiple zones. The divided zones may also be called a mesh. Within an area covered by the distribution station a common control signal or a cognitive pilot channel is distributed. A method of utilizing a radio resource such as basic parameter information, etc., of a radio system is reported multiple times for each mesh from the distribution station. Information reported is the same, and does not depend on the times.
Moreover, as a method of distributing a common control signal, there are two types, a notice-type distribution method and an on-demand type distribution method. In the notice-type distribution method, the distribution station periodically distributes control information for a mesh within a region of which the distribution station is in charge. In the on-demand type distribution method, the distribution station distributes control information for a mesh requested by the terminal apparatus in response to a request for distribution from the terminal apparatus. Moreover, a method is also proposed which combines the notice-type distribution method and the on-demand type distribution method and switches between the distribution methods according to information to be distributed. The on-demand type distribution method is disclosed in Non-patent document 1.
Non-patent document 1: J. Perez-Romero, et al., “A Novel On-Demand Cognitive Pilot Channel enabling Dynamic Spectrum Allocation,” IEEE Dyspan 2007